Endodontic files having improved lateral and torsional flexibility

Abstract

A dental reamer/file instrument having an elongated shank having a proximal end portion, a distal end and an intermediate tapered working portion, the external surface of the shank working portion having three continuous equally spaced helical flutes forming three spiral flanges, each of which, in a plane perpendicular to the length of the shaft is defined in part by a triangular outer working portion having a base width of “A”, an apex of each triangular outer portion forming a cutting/scraping edge, each triangular outer working portion being integrally connected to the central core portion by a reduced width neck portion of width “B” and wherein “A” is greater than “B”, the triangular outer working portions being rotational flexibility within elastic limits relative to the shaft central core portion.

1 . A dental reamer/file instrument comprising: 
 an elongated shank having a proximal end portion, a distal end and a tapered working portion extending from said proximal portion to said distal end;    the external surface of said shank working portion being defined in part by three continuous helical flutes formed into a central core portion of said shank working portion and equally spaced about the circumference of said shank working portion the flutes being spaced apart to define three spiral flanges, each of which is, in a plane perpendicular to the length of said shaft, defined in part by a triangular outer portion having a base width of “A”, an apex of each triangular outer portion forming a cutting/scraping edge, each said triangular outer portion being integrally connected to said central core portion by a reduced width neck portion of width “B” and wherein “A” is greater than “B”, said triangular outer portions having rotational flexibility relative to said shaft central core portion.    
   
   
       2 . A dental reamer/file instrument according to  claim 1  wherein the depth of said helical flutes are selectably variable, the torsional flexibility of the reamer/file instrument increasing as the depth of said flutes increases.  
   
   
       3 . A dental reamer/file according to  claim 1  wherein said triangular outer portion forms a right angle apex.  
   
   
       4 . A dental reamer/file according to  claim 1  wherein said triangular outer portion forms an acute angle apex.  
   
   
       5 . A dental reamer/file according to  claim 1  wherein said triangular outer portion forms an obtuse angle apex.  
   
   
       6 . A dental reamer/file instrument comprising: 
 an elongated shank having a proximal end portion, a distal end and a tapered working portion extending from said proximal portion to said distal end;    the external surface of said shank working portion being defined, in part, by at least one continuous helical flute formed into a central core portion of said shank working portion to provide a spiraled flange for each helical flute, each spiral flange being defined in part by an outer portion having a width of “A”, each outer portion defining a spiraled cutting or scraping edge, each said outer portion being integrally connected to said central core portion by a reduced width neck portion of width “B” and wherein “A” is greater than “B”, each said outer portion being rotationally flexible within elastic limits relative to said central core portion.